Object Instantiation

• In the Java nio model, a file is uniquely identified by a path object.
• In Java - Java IO, file instances represent file or directory names.

File f = new File("myFileName.txt");

Creation

with the nio library

Path path = Paths.get("target/example.txt");
Files.createFile(path);

Read

• FileReader use the default encoding.

FileReader fileReader = new FileReader(file);
FileReader fileReader = new FileReader(path.toFile());

• With encoding

new InputStreamReader(new FileInputStream(filePath), encoding)

Write

• Java - (Nio|New I/O) Package

BufferedWriter writer = Files.newBufferedWriter(path, Charset.UTF8, StandardOpenOption.APPEND)

Get the file extension

• with Java - (Nio|New I/O) Package

static private String getFileExtension(Path path) {
	String name = path.getFileName().toString();
	try {
		return name.substring(name.lastIndexOf(".") + 1);
	} catch (Exception e) {
		return "";
	}
}

Meta Information

• with Java - (Nio|New I/O) Package, you access the file system with the Files class

Path myFile = Paths.get("D:\\temp\\temp.txt");
System.out.println("The file exists ?: "+Files.exists(myFile));
System.out.println("The file size in bytes is: "+Files.size(myFile));
System.out.println("The file is a regular file? : "+Files.isRegularFile(myFile));
System.out.println("The file is readable? : "+Files.isReadable(myFile));
System.out.println("The file is executable? : "+Files.isExecutable(myFile));

The file exists ?: true
The file size in bytes is: 13346941
The file is a regular file? : true
The file is readable? : true
The file is executable? : true

• with Java - Java IO

if(f.exists()) { /* do something */ }
if(f..isFile()) { /* do something */ }

Equality

• with Java - (Nio|New I/O) Package

System.out.println("The file and the directory are equal? : "+Files.isSameFile(myFile, myDirectory));

The file and the directory are equal? : false

From file to string

with Java - Java IO

import org.apache.commons.io.IOUtils;
FileInputStream in = new FileInputStream(files[i]);
String sqlStatement = IOUtils.toString(in);
in.close();

Temporary

// Write the final in the Java directory system property ''java.io.tmpdir''
File tempFile = File.createTempFile(prefix, suffix)

String tempDir = System.getProperty("java.io.tmpdir");

# see also:
Files.createTempFiles 
...